The Cisco Discovery Protocol (CDP) service allows your device to find the voice VLAN advertised by the switch. If it's present, your device will then communicate with the voice VLAN instead of the default VLAN.
The CDP service only works if your device is using a wired Ethernet network connection. The CDP service is on and running by default. To change the setting:
Open the control panel on your device by swiping from the right side of the screen or selecting the button. Then select Device Settings.
Scroll to and select Network connection and then Ethernet .
Toggle CDP (Cisco Discovery Protocol) ON or OFF.
When you're finished, tap the checkmark at the top right of the menu.